Positive and Negative Numbers

What is…

… a positive number? A number that is greater than zero

… a negative number?

A number that is less than zero.

…an opposite number?

Numbers that are the same distance from zero in the opposite direction.

…an integer?

All whole numbers and their opposites on a number line

9 opposite -9

This is a number line

negative positive

Using positive and negative numbers…

Is like driving in traffic. You have to watch for the signs!

This is the positive sign!

This is the negative sign!

Hint:

If you don’t see a sign in front of a number, don’t panic! No sign means it is a positive number!

Addition Rules

If the signs are the same, cross them out and pretend they are not there and add as you normally would.

After adding the numbers together, place the sign in front of the answer.

Adding Integers with the same sign:

Take away the signs and get this:

3+5=8

Rule # 2:

If the signs are different, pretend they are the same and subtract the smallest number and add the sign of the largest number to your answer.

For Example:

Subtract the numbers normally and add the sign of the largest number:

5-3=2 add sign =-2

Solve these problems:

3+-8 5+-9 -8+-2 9+9

-5+-9 3+9 -7+4

10+-4

One way to add numbers is by using the number line.

When a number is positive, count to the right

When a number is negative, count to the left

Now we’re all pros at adding positive and negative numbers!